Military submarines are highly complex machines which proved to be relatively safe for the submariners aboard them. However, serious accidents did happen in the past and there is always the risk that some may happen in the future. Any submariners must then be ready for all kinds of emergencies and training is an essential part of this preparation. Extensive training is often a factor that allowed people to come out of difficult situations without any or serious harm.
Among all potential dangers of being in a submarine, one of them is to be stuck underwater with no other option but to leave the submarine before outside help can arrive. Some naval forces do have small submarines which can be attached over a hatch and provide an escape vehicle to leave a submerged submarine in distress. Unfortunately, it is not always possible to use such vehicle since it is almost never immediately available. Submariners must then be able to leave a submerged submarine by themselves if that is required. This is the reason why military submarines are conventionally provided with one or more exits called “escape towers”. One escape tower is usually provided near the front of the submarine and one at the rear.
Escape suits conventionally found in submarines allow the submariners to escape without pressurized air from a compressed air cylinder. One of the reasons is that there are many persons in a military submarine so that the number of air cylinders would be too important. Another reason is that air inside a submarine is not pressurized and is maintained at the sea level. There are thus no decompression stages to follow in that case.
An escape suit is designed to be watertight and air inflatable. An example of suit is the “Mark X” escape suit. The suit is used with glove and a nose clip. The escape suit keeps the submariner dry and warm while he is in water or aboard a life raft. Air inside the suit increases the thermal insulation. Once inflated, the suit also allows the submariner to quickly reach the surface. The suit is equipped with a hood inflation system (HIS) which further allows the submariner to keep his face out of the water. The HIS consists of a hood, partly made of transparent plastic, which completely covers the head and face of the person. Small air vents in the suit, at the upper chest, allow air to flow from the suit into the hood compartment. A small space is maintained between a part of the hood on the chest and the outside. The HIS retains air therein, thereby allowing the head to remain clear of the water and the submariner to breathe if necessary. However, during an ascent, the submariner must expel air. Pressurized air is forced into the escape suit immediately before leaving the submarine through the escape tower. This is possible by using a push fit connector insertable in a pressurized air outlet called a “stole charging valve”.
Escape suits are usually equipped with a compact individual raft to be inflated once at the surface using a CO2 canister. This allows the submariner to get out of the water and wait for rescue. The rafts of two or more persons may be attached together so as to facilitate the search and rescue operations. Usually, the first vehicle to reach the scene in a search and rescue operation is an airplane. The airplane typically drops one or more large life rafts provided with supplies. Submariners climb on board these larger rafts and wait for surface rescue or rescue helicopters to arrive.
Training for escaping out of a submerged submarine through the escape tower was usually done without ever having the submariners experiencing the complete escape procedures itself. Submarines are not adequate locations for this kind of training because the escape procedure involves a certain level of danger. Some hands-on training was possible only using fixed towers filled with water and at the bottom of which a submariner can exit through a hatch and experience an assent using the submarine escape suit. One of such training facility is located in Gosport, United Kingdom.
Considering this background, it clearly appears that there was a need to provide a simulator and a method of performing underwater submarine escape training in a body of water, thereby allowing submariners to have hands-on training on submarine escape procedures in a controlled and safe environment.